1. Field of the Invention
The present invention generally relates to check valves in communication with a vacuum system.
2. Description of the Related Art
Non-return valves, also known as check valves, are generally configured to control the direction of a gas and/or liquid flow through a conduit. More particularly, a typical non-return valve operates to permit a gas and/or liquid flow in one direction, while prohibiting the same gas and/or liquid from flowing in an opposite direction. Therefore, non-return valves are very useful as safety devices, as they may be utilized to prevent back streaming of toxic and/or corrosive gases into a gas supply.
In the semiconductor manufacturing industry, for example, non-return valves are often used as a safety device positioned between a house gas supply and a semiconductor fabrication device. In this implementation, the non-return valve maybe positioned such that the gas flow is allowed to travel in the direction of the semiconductor fabrication device from the house gas supply. Therefore, gases may be provided to the semiconductor fabrication device, but not allowed to reverse the direction of flow and return to the house gas supply. As such, in the situation where a plurality of gases are mixed in a gas supply leading to a semiconductor manufacturing device, the mixture of gases is not allowed to then flow back into a pure gas supply house, which would then contaminate the entire gas supply.
Generally, there are two types of non-return valves: first, actuated non-return valves, and second, non-actuated and/or biased flow control valves. Actuated flow control valves generally include an actuator, such as a solenoid, built into the valve body into the actuated non-return valve, such that the solenoid/actuator may be activated to selectively open and/or close the non-return valve. Therefore, an electrical signal indicating to the solenoid and/or actuation device that the non-return valve is to be opened/or closed is generally required in order to operate the actuated non-return valve. Therefore, actuated non-return valves are generally in communication with an electronic controller, wherein the electronic controller is configured to sense a flow pressure differential across the actuated non-return valve in order to determine when the actuated non-return valve should be opened and/or closed to provide proper gas flow. For example, if the valve controller determines that the pressure differential across the actuated non-return valve is, for example, one-third PSI wherein the greater pressure is present on the front side of the valve, then the controller may be configured to close the non-return valve, as a gas back-flow situation is present.
Alternatively, non-actuated and/or biased non-return valves operate to prevent back-flow without using an actuator. Generally, non-actuated, non-return valves utilize a spring and/or biasing device in communication with a valve opening/closing device, wherein the spring and/or biasing device is configured to provide force sufficient to close the valve opening and/or closing device when a back-flow situation occurs. For example, a non-return valve may include a valve plunger configured to open and/or close in order to allow gas to flow and/or be stopped through the non-return valve. A biasing spring may be in communication with the valve plunger such that the biasing spring biases the valve plunger to a closed position. However, when sufficient pressure is present on the back side of the non-return valve, this pressure operates to open the valve plunger and allow gas to flow through the non-return valve, assuming that the gas pressure is sufficient to overcome the biasing force applied to the valve plunger by the biasing spring. Therefore, in similar fashion to actuated non-return valves, when the pressure on the front side of the non-return valve becomes greater than the pressure on the back side of the non-return valve, i.e., when the gas supply pressure is less than the gas back-flow pressure, then the biasing spring operates to bias the valve plunger to a closed position and prevent gas back-flow.
Although actuated and non-actuated non-return valves generally provide acceptable operational characteristics, non-actuated non-return valves have some advantages over actuated non-return valves. In particular, non-actuated non-return valves do not require an electronic controller and/or pressure sensors in order to effectively prevent gas back-flow and/or back streaming into gas supply sources. As such, not only is the need for additional control devices eliminated, the number of potential trouble shooting elements in a failure situation is minimized. Further, since non-actuated non-return valves do not require external controllers and/or electrical impulses, non-actuated non-return valves provide an additional level of safety, as the valves automatically close in power outage-type situations.
However, non-actuated non-return valves suffer from a disadvantage, in that they generally do not allow for full evacuation of the gas end or fluid conduit, as the non-actuated non-return valve will close when the pressure on the front side of the valve becomes equal to and/or slightly greater than the pressure on the back side of the valve. In the semiconductor manufacturing industry, for example, this is a substantial disadvantage, as it is very difficult and/or impossible to achieve effective out gassing of the conduit line and/or to find small leaks in the line.
Therefore, there exists an need of a non-actuated non-return valve, wherein the valve is configured to receive a manual override, so that out gassing and/or leak checking operations may be conducted on the conduit in communication with the back side (supply side) of the non-return valve.
Embodiments of the invention generally provide an improved non-actuated non-return valve, the valve including a non-magnetic valve body having a substantially hollow interior portion in communication with a gas inlet and a gas outlet. A mechanically biased flow check assembly is positioned within the substantially hollow interior portion, the mechanically biased flow check assembly being configured to permit a gas flow from the gas inlet to the gas outlet. A first magnetic member may be provided and be in communication with the mechanically biased flow check assembly within the substantially hollow interior portion. A second magnetic member detachably positioned adjacent an exterior portion of the valve body may be provided, wherein a magnetic field of the second magnetic member is configured to impart motion to the mechanically biased flow check assembly when positioned proximate the exterior portion of the valve body.
Embodiments of the invention further provide an improved non-return valve having a valve body and a substantially hollow interior portion. The valve further includes a non-actuated flow check assembly positioned between a gas inlet and a gas outlet, the gas inlet and gas outlet being in communication with the substantially hollow interior portion. A first magnetic device in mechanical communication with the flow check assembly is provided, and a magnetic member detachably positioned proximate an exterior portion of the valve body is included, wherein a magnetic field of the second magnetic member is configured to impart motion to the non-actuated flow check assembly when positioned proximate the exterior portion of the valve body.
Embodiments of the invention further provide an improved non-actuated non-return valve, the valve including a valve body having a substantially hollow interior portion and a non-actuated flow check assembly positioned between a gas inlet and a gas outlet, the gas inlet and gas outlet being in communication with the substantially hollow interior portion. The valve further includes a means for interacting with a magnetic field in mechanical communication with the flow check assembly, and a means for generating a magnetic field detachably positioned proximate an exterior portion of the valve body. The valve being configured such that the magnetic field of the means for generating a magnetic field is configured to impart motion to the non-actuated flow check assembly via the means for interacting with a magnetic field when the means for generating a magnetic field is positioned proximate the exterior portion of the valve body.
Embodiments of the invention further provide a method for mechanically actuating a non-actuated non-return valve. The method includes the steps of positioning a first magnetic device on a flow check assembly within the non-actuated non-return valve, and positioning a second magnetic device proximate an exterior portion of the non-actuated non-return valve. The positioning steps are configured to that a magnetic field generated by the second magnetic device operates to actuate the flow check assembly to an open position.